Unit 15. Mammals.

WARM-UP: Write five words for each category.

VOCABULARY: Learn the following words and word combinations.

immature to nourish bat aardvark beaver sloth hamster whale monotreme duck-billed platypus spiny anteater belly marsupial ape pouch to hop to be in danger of extinction mob herbivore uterus rodent carnivore cub omnivore insectivore pangolin

Guess the meaning of the following words.

Warm-blooded animals; to lay eggs; to hatch; urinary tract; shell; metabolic rate; muscular tail; mammals; in the wild; nocturnal; to chew; to swallow; placenta; nutrients; oxygen; embrionoc organ; venomous.

Practice the following for pronunciation.

Nourish ['nʌrɪʃ]

ape [eɪp]

aardvark [ˈɑːdˌvɑːk]

monotreme [ˈmɒnəʊˌtriːm]

duck-billedplatypus [ˈplætɪpəs]

echidna [ɪˈkɪdnə]

cloaca [kləʊˈeɪkə]

urinary tract [ˈjʊərɪnərɪ]

anus [ˈeɪnəs]

anteater [ˈæntˌiːtə]

pouch [paʊtʃ]

marsupial [mɑːˈsjuːpɪəl]

immature [ˌɪməˈtjʊə]

numbat [ˈnʌmˌbæt]

cretaceous period [krɪˈteɪʃəs]

regurgitate [rɪˈgɜːdʒɪˌteɪt]

placental [[pləˈsɛntl]

beaver [ˈbiːvə]

extinction [ɪkˈstɪŋkʃən]

READING: Read the text and do the tasks that follow.

Mammals are animals that have hair, are warm-blooded, and nourish their young with milk. Some modern-day mammals include people, apes, cats, bats, dogs, tigers, mice, aardvarks, beavers, elephants, gorillas, sloths, pandas, hamsters, horses, whales, and dolphins.

Monotremes are the most primitive mammals. There are three species of monotremes, the duck-billed platypus and two spiny anteaters, or echidnas. These mammals lay eggs; after the babies hatch, the mothers nourish their young with milk. Today, monotremes live only in Australia and New Guinea. The name monotreme means "one-holed," referring to the cloaca, a single hole that serves the urinary tract, anus, and reproductive tract in monotremes. Monotremes lay tiny eggs (less than 2 cm long) that have a leathery shell. The young get milk from a gland on the mother's belly. The platypus lays her eggs on the bank of a stream, then curls around the eggs to protect them and keep them warm. Spiny anteaters lay a single egg in a temporary protective pouch on the mother's belly. Monotremes have hair like other mammals, and the females produce milk. They have a low metabolic rate and a temperature slightly lower than that of placental mammals.

Marsupials are another group of mammals; their young are born in an extremely immature state; most female marsupials have pouches. Some marsupials include the koala, kangaroo, and the numbat. Marsupials are pouched mammals whose babies are born in a very undeveloped state; the young then attach themselves to their mother's nipple. Many marsupials have a pouch that encloses the young.

The biggest marsupial is the human-sized red kangaroo; the smallest marsupial, the pilbara, would fit in a person's hand. Some commonly-known marsupials include the kangaroo, opossum, Tasmanian devil, and koala. The only marsupial in North America is the Virginia opossum.

Marsupials evolved during the late Cretaceous period, about 100 to 75 million years ago, during the time of the dinosaurs.

The Kangaroo is a common marsupial from the islands of Australia and New Guinea. There are 47 species of "roos." Kangaroos can hop up to 40 miles per hour and go over 30 feet in one hop. When standing, roos often use their muscular tail as an extra leg. These shy animals live about 6 years in the wild and up to 20 in captivity. Most roos are nocturnal. Many roos are in danger of extinction, but they are also considered pests due to the way they damage crops. An adult male is called a buck, boomer or jack; an adult female is called a doe, flyer, roo, or jill. A baby is called a joey. A group of roos is called a mob.

These herbivores (plant-eaters) eat grass, leaves, and roots. They swallow their food without chewing it and later regurgitate a cud and chew it. Roos need little water; they can go for months without drinking, and they dig their own water wells.

Placental mammals are mammals whose young are born at a relatively advanced stage (more advanced than the young of other mammals, the monotremes and marsupials). Before birth, the young are nourished through a placenta. The placenta is a specialized embryonic organ that is attached the mother's uterus and delivers oxygen and nutrients to the young. Most mammals are placental mammals, like cats, dogs, horses, and people. There are almost 4,000 known species of placental mammals. There are more rodents and bats than other types of placental mammals.

Mammals have to eat a lot to maintain their high body temperature. Diets vary from genus to genus. As with most animal groups, there are more herbivores (plant-eaters) than there are carnivores (meat-eaters).

Types of Mammalian Diets:

Herbivores (plant eaters) - including beavers, cows, horses, pandas, sloths, and others

Carnivores (meat eaters) - including whales and dolphins, dogs, tigers, lions, and others

Omnivores (eat plants and meat) - people, some bears, and others

Insectivores (eat insects) - aardvarks, anteaters and others

Only a few mammals are venomous, including the duckbilled platypus (males only), several species of shrews, and the Solenodon (a small insectivore).